Portable devices such as mobile phones, laptop computers, tables, and other communication device primarily rely on electrical battery energy to operate and conduct communications. Electrical batteries store chemical energy and deliver electrical energy through an electrochemical conversion process. Electrical batteries may be non-rechargeable or rechargeable. Although some portable devices may use non-rechargeable batteries, the vast majority depend on rechargeable batteries.
To recharge, conventional power transfer into portable devices requires these devices to be plugged into an electrical outlet. Although wireless data transmission is commonplace, wireless power transmission is not, except at extremely low power levels and not in an effective form for many applications. One impediment to wireless power transmission is the diffusion and diffraction of electromagnetic waves which is the conventional wireless transmission of electrical power. Consequently, this spreads out the available energy so that only a tiny fraction is available at the receiving end.
Nevertheless, manufacturers have begun producing wireless battery charging stations. They operate under the principle of electromagnetic (EM) induction. electromagnetic induction is well known in the art and involves coupling the magnetic field generated by an external coil with an implanted coil (Schuder, 1960; Van Schuylenbergh and Puers, 2009). As the name connotes, wireless charging pads recharge portable device batteries and forego the necessity of connecting wires.
Other disclosures, e.g., patent Pub. No. US 2013/0241468 A1 (Moshfeghi, 2013) disclose battery charging using an array of transducers and a power combiner connected to a battery charger. These systems are costly and difficult to manufacture and maintain and have other operational limits with respect to the power and frequency range of their operation, which make them non-ideal for some applications as discussed below.
With the proliferation of wireless devices, electromagnetic interference amongst devices will become an increasing problem with electromagnetic induction charging. In general, electromagnetic waves are incoherent and tend to spread out spatially while propagating. Electromagnetic systems also depend on a progressively crowded frequency space shared with other devices. Both electromagnetic stray fields (noise) from diffusion and bandwidth encroachment can interfere with the operation of nearby devices that are sensitive to such interference.
Although a useful method, electromagnetic induction charging has other limitations. To achieve sufficient power at the receiver, the power level at the transmitter becomes impractically high. Additionally, to focus a useable amount of energy to the transmitter requires physically large antennas. This is due to the focusing antennas having to be many times larger than the wavelength of the transmitted radiation.
Furthermore, there is difficulty of controlling the impedance matching as a function of transmitter and receiver alignment. That in turn reduces the efficiency of transmission, leading to heating of the electronic devices themselves, causing, in some cases, their failure. There are also issues relating to safety and electromagnetic interference to other electronic devices.
Therefore, there exists a need for an electric power charging system using directional power propagation without the threat of electromagnetic interference and bandwidth infringement of other devices.
Other problems exist in the automotive industry. For example, underinflated automotive tires are the cause of many avoidable accidents. Since manually checking the tire pressure is inconvenient, it is often neglected by the motorist. Several systems have been developed and deployed to automate this process, but they all have shortcomings. Indirect tire pressure monitoring systems (TPMSs) suffer inaccuracy and are plagued with a high percentage of false positives as well as false negatives. Direct TPMSs (DTPMs) require batteries that must be replaced at regular intervals and are prone to failure due to harsh environmental conditions, such as vibration, shock and extreme temperatures.
Powering of TPMS sensors has been attempted using micro machined electro mechanical systems (MEMS) embedded in the tire assembly with the TPMS. The powering of these MEMS units is based on energy harvesting resulting from the movement of the tires during the automobile's motion. However, these systems have proven to be unreliable as a powering source due to the difficulty in harvesting useful power from relatively unpredictable types of motion during the automobile's movement. Examples of existing TPMSs are disclosed in U.S. Pat. No. 6,175,302, titled “Tire Pressure Sensor Indicator Including Pressure Gauges That Have a Self-Generating Power Capability,” U.S. Pat. No. 8,011,237, titled “Piezoelectric Module For Energy Harvesting, Such As In a Tire Pressure Monitoring System,” and U.S. Pat. No. 9,484,522, titled “Piezoelectric Energy Harvester Device With Curved Sidewalls, System, And Methods Of Use And Making.”
Therefore, there exists a need for more accurate and more reliable systems to automatically check tire pressure on vehicles.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the present disclosure and claims.